STAMPER AND METHOD PRODUCING THE SAME
According to one embodiment, a stamper includes patterns corresponding to recording tracks or recording bits in a data region and patterns corresponding to information in a servo region formed in protrusions and recesses on a front side of the stamper, in which an inner periphery and an outer periphery are processed and, on a back side, an inner peripheral edge, an outer peripheral edge and a main surface of the back side lie on the same plane.
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This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-020693, filed Jan. 30, 2009, the entire contents of which are incorporated herein by reference.
BACKGROUND1. Field
One embodiment of the present invention relates to a stamper and a method of producing the same.
2. Description of the Related Art
Recently, in a magnetic recording medium installed in hard disk drives (HDDs), there is an increasing problem of disturbance of enhancement of track density due to interference between adjacent tracks. In particular, a serious technical subject is reduction in fringing of a magnetic field from a write head.
To solve such a problem, a discrete track recording medium (DTR medium) has been developed in which recording tracks are physically separated from each other. Since the DTR medium can reduce a side-erase phenomenon in writing and a side-read phenomenon in reading, it can increase the track density. Therefore, the DTR medium is expected as a high-density magnetic recording medium.
Also, a bit patterned medium (BPM) has been developed in which read and write are performed for a single magnetic dot as a single recording cell have been developed as a high-density magnetic recording medium that can suppress thermal fluctuation phenomenon and medium noise.
To produce individual DTR media or BPMs by electron beam (EB) lithography highly increases production cost. In this connection, it is effective in reducing the production cost to produce DTR media or BPMs in such a manner that an Ni stamper is produced from a master plate on which fine patterns are formed by electron beam (EB) lithography, many resin stampers are produced from the Ni stamper by injection molding, and DTR media or BPMs are produced from the resin stampers by UV imprint (UV curing imprint). This method enables to mass-produce the DTR media or BPMs at low cost.
A similar technology is adopted for production of optical disks. When optical disks are produced from an Ni stamper by injection molding, it is known that the Ni stamper can endure 100,000 shots of the injection molding.
However, it was found that, when the resin stampers for producing the DTR media or BMPs by injection molding are produced from a Ni stamper, the Ni stamper deforms to an extent that exceeds an allowable range after several thousand shots and also a shape of the resin stampers deteriorates. This is considered to be because fineness of patterns of the DTR medium or BMP are one tenth or less of that of patterns of an optical disk, and thus it is necessary to apply mold clamping force as high as 50 to 70 tons during injection molding.
Jpn. Pat. Appln. KOKAI Publication No. 5-2775 discloses a method of polishing the back side of a stamper to keep uniformity of an optical disk surface. However, even when resin stampers for producing the DTR media or BPMs are produced by adopting the method described in Jpn. Pat. Appln. KOKAI Publication No. 5-2775, the lifetime until the Ni stamper deforms exceeding an allowable range cannot be improved.
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, there is provided a stamper comprising: patterns corresponding to recording tracks or recording bits in a data region and patterns corresponding to information in a servo region formed in protrusions and recesses on a front side of the stamper, wherein an inner periphery and an outer periphery are processed and, on a back side, an inner peripheral edge, an outer peripheral edge and a main surface of the back side lie on the same plane.
According to another embodiment of the invention, there is provided a method of producing a stamper, comprising: applying an electron beam resist to a substrate; drawing pattern corresponding to recording tracks or recording bits in a data region and patterns corresponding to information in a servo region on the electron beam resist by electron beam lithography, followed by developing to form protrusions and recesses; forming a conductive film on the protrusions and recesses of the electron beam resist followed by forming a Ni electroforming layer by electroforming; peeling off the Ni electroforming layer to form a stamper; duplicating a stamper by repeating forming and peeling-off of the Ni electroforming layer, as required; and processing an inner periphery and an outer periphery of the stamper followed by polishing a back side of the stamper.
The inventors studied the reason why a lifetime until an Ni stamper deforms to an extent exceeding an allowable range becomes shorter when resin stampers for producing DTR media or BPMs are produced from the Ni stamper by injection molding. As a result, it was found that when there are burrs on a back side of the Ni stamper and the stamper is set to a mold of an injection molding machine, a gap is formed between the mold and the stamper. Further, when mold clamping force as high as 50 to 70 tons is applied to the structure, high load is applied to the Ni stamper to cause deformation. Herein, the burr is defined as a protrusion having a height exceeding the surface roughness (Ra) of a main surface of a back side free from burrs.
The burrs on the back side of the Ni stamper are generated when inner and outer peripheries of the stamper are pressed with a punching blade. At this time, heights of the burrs generated at the inner and outer peripheries of the stamper are usually about 15 μm. In a conventional method, a protective film is applied to a front side (a side on which patterns are formed) of the produced Ni stamper, the back side thereof is polished, and thereafter the inner and outer peripheries of the stamper are pressed. Therefore, at the time of injection molding, burrs remain.
According to the method of the invention, a back side is polished after the inner and outer peripheries of the stamper are processed. Therefore, there is no burr remaining during the injection molding. As a result, a gap is hardly formed between the mold and the stamper when the stamper is set to the mold of the injection molding machine and, even when mold clamping force as high as 50 to 70 tons is applied, high load is difficult to be applied on the Ni stamper, resulting in a prolonged lifetime until deformation is caused in the Ni stamper.
Embodiments of the invention will be described below with reference to drawings.
In the invention, there is produced a stamper where patterns corresponding to recording tracks or recording bits in the data region and patterns corresponding to information of the servo region of the DTR medium shown in
A method of producing a Ni stamper according to an embodiment of the invention will be described below with reference to
As shown in
As shown in
As shown in
Nickel sulfamate: 600 g/L
Boric acid: 40 g/L
Surfactant (sodium lauryl sulfate): 0.15 g/L
Temperature of a solution: 55° C.
pH: 4.0
Current density: 20 A/dm2.
As shown in
As shown in
As shown in
As shown in
Next, with reference to
First, the Ni stamper 55 produced according to the method described with reference to
As shown in
As the metal layer 74, a metal excellent in the adhesiveness with a UV resist (photopolymer agent, 2P agent) described below and completely stripped off during etching with He+N2 gas described below is used. Specific examples thereof include CoPt, Cu, Al, NiTa, Ta, Ti, Si, Cr, NiNb and ZrTi. In particular, CoPt, Cu and Si are excellent in both the adhesiveness with the UV resist and stripping properties by the He—N2 gas.
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
Next, with reference to
As shown in
As shown in
The mother stamper is more suitable than the father stamper when resin stampers for producing DTR media or BPMs are produced. This is because patterns formed on the DTR medium or BPM are the same as patterns drawn with the EB drawing apparatus.
A time necessary for EB drawing is generally 3 to 4 days for a 1.8 inch DTR medium and one week for a 2.5 inch DTR medium. Accordingly, it is preferable to be able to duplicate stampers from the viewpoint of mass-productivity.
With reference to
As shown in
As shown in
When the above-mentioned method is repeated, a lot of duplication stampers may be mass-produced from the father stamper.
Advantages of the invention will be described below in more detail. As described above, when a stamper is produced according to the method of the invention, the back side of the stamper is free from burrs, and an inner peripheral edge, an outer peripheral edge and a main surface of the back side lie on the same plane on the back side. Accordingly, a lifetime of the stamper is largely extended during injection molding.
The resin stamper prepared according to the method of the invention and DTR media or BPMs produced therewith are found to be smaller in RRO (repeatable run out) than ever. The RRO is also called a positional distortion in track synchronization and represents a deviation of a track from a true circle. In a stamper prepared according to a conventional method, burrs remaining on an inner periphery and an outer periphery collapse every time injection molding is repeated to result in generating distortion in the stamper itself. As a result, the RRO increases in the resin stamper and the DTR media or BPMs produced therewith.
The stamper prepared according to the method of the invention is excellent as well in safety. The inner peripheral edge and outer peripheral edge of the stamper produced according to a conventional method are formed into a form like a sharp blade. Accordingly, there is a possibility that careless handling may hurt a hand. The inner peripheral edge and outer peripheral edge of the stamper prepared according to the method of the invention are polished. Accordingly, a touch with a hand does not cause injury.
The stamper prepared according to the method of the invention may suppress warping. It is known that when a resin stamper is formed from a warped Ni stamper by injection molding and DTR media or BPMs are produced with the resin stamper, the RRO increases. Thus, it is preferable that the warping of the Ni stamper is preferably as small as possible. In the stampers prepared according to a conventional method, a radial tilt may be substantially ±0.6° in some cases. However, in the stampers prepared according to the method of the invention, the radial tilt may be suppressed to substantially ±0.2°. The phenomenon may be described as follows. In a process of polishing a back side, stress is applied on the Ni stamper to generate strain; however, the Ni stamper does not warp in this state. In a conventional method, it is considered that since punching is performed under high internal stress, the stress is alleviated at one stroke during punching, and thereby warp is generated in the Ni stamper. In the invention, it is considered that since punching is performed before the back side is polished, the stress is not alleviated and thereby the Ni stamper is inhibited from warping.
The method of the invention is also effective for inhibiting dust from adhering. A back side of a Ni stamper is mirror-polished by buffing. After the step, a cleaning step for removing slurry adhered to the back side is performed. According to a conventional method, inner and outer peripheries are punched after the mirror polishing. Therefore, grinding sludge generated during punching remains as adhered. According to the method of the invention, after the inner and outer peripheries are punched and the back side is mirror-polished, a cleaning step is performed. Thus, grinding sludge may be removed and adhering dust becomes less. Accordingly, yield improvement and cost reduction may be achieved.
Materials and individual steps used in the invention will be detailed below.
[UV Resist]
A UV resist (2P agent) is a material having UV-curability and a composition containing a monomer, an oligomer and a polymerization initiator but not a solvent.
Examples of the monomer include those shown below.
-
- Acrylates
Bisphenol A.ethylene oxide-modified diacrylate (BPEDA)
dipentaerythritol hexa(penta)acrylate (DPEHA)
dipentaerythritol monohydroxy pentaacrylate (DPEHPA)
dipropylene glycol diacrylate (DPGDA)
ethoxylated trimethylolpropane triacrylate (ETMPTA)
glycerinpropoxy triacrylate (GPTA)
4-hydroxybutyl acrylate (HBA)
1,6-hexanediol diacrylate (HDDA)
2-hydroxyethyl acrylate (HEA)
2-hydroxypropyl acrylate (HPA)
isobornyl acrylate (IBOA)
polyethylene glycol diacrylate (PEDA)
pentaerythritol triacrylate (PETA)
tetrahydrofurfuryl acrylate (THFA)
trimethylolpropane triacrylate (TMPTA) tripropylene glycol diacrylate (TPGDA)
-
- Methacrylates
tetraethylene glycol dimethacrylate (4EDMA)
alkyl methacrylate (AKMA)
allyl methacrylate (AMA)
1,3-butylene glycol dimethacrylate (BDMA)
n-butyl methacrylate (BMA)
benzyl methacrylate (BZMA)
cyclohexyl methacrylate (CHMA)
diethylene glycol dimethacrylate (DEGDMA)
2-ethylhexyl methacrylate (EHMA)
glycidyl methacrylate (GMA)
1,6-hexanediol dimethacrylate (HDDMA)
2-hydroxyethyl methacrylate (2-HEMA)
isobornyl methacrylate (IBMA)
lauryl methacrylate (LMA)
phenoxyethyl methacrylate (PEMA)
t-butyl methacrylate (TBMA)
tetrahydrofurfuryl methacrylate (THFMA)
trimethylolpropane trimethacrylate (TMPMA)
In particular, isobornyl acrylate (IBOA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), neopentyl glycol diacrylate (NPDA) and ethoxylated isocyanuric acid triacrylate (TITA) are preferred because these may have viscosity of 10 cP or less.
Examples of the oligomer include urethane acrylate-bases materials such as polyurethane diacrylate (PUDA) and polyurethane hexaacrylate (PUHA), and other examples include polymethyl methacrylate (PMMA), fluorinated polymethyl methacrylate (PMMA-F), polycarbonate diacrylate, and fluorinated polycarbonate methyl methacrylate (PMMA-PC-F).
Examples of the polymerization initiator include IRGACURE 184 (trade name, manufactured by Nihon Ciba-Geigy K. K.) and DAROCURE 1173 (trade name, manufactured by Nihon Ciba-Geigy K. K.).
[Removal of Residues]
Residues remaining at bottoms of recesses of the resist are removed by RIE (reactive ion etching). As a plasma source, ICP (inductively-coupled plasma) capable of forming high density plasma at low pressure is preferred. However, ECR (electron cyclotron resonance) plasma or a general parallel plate RIE apparatus may be used. Residues of the UV resist (2P agent) are removed preferably with an oxygen gas.
[Demagnetization and Etching]
When flying characteristics of a read/write head are taken in consideration, a depth of recesses is preferably set at 10 nm or less, while a thickness of a magnetic recording layer needs to be substantially 15 nm for securing signal output. In this connection, if a thickness of 10 nm in the magnetic recording layer with a thickness of 15 nm is physically removed and a remaining thickness of 5 nm is demagnetized, side erase and side read may be suppressed while securing the flying characteristics of the recording head. This makes it possible to produce DTR media and BPMs. As a method of demagnetizing the magnetic recording layer having a thickness of 5 nm, a method of exposing the magnetic recording layer to He or N2 ions may be used. When the magnetic recording layer is exposed to He ions, while maintaining squareness of a hysteresis loop, Hc (coercivity) decreases with an exposure time to result in losing the hysteresis eventually (demagnetization). In this case, when an exposing time to a He gas is insufficient, the hysteresis excellent in the squareness (having reversal nucleation field Hn) is maintained. However, this means that a magnetic layer at the bottom of the recess has recording capacity, that is, advantages of the DTR medium or BPM are lost. On the other hand, when the magnetic recording layer is exposed to N2 ions, the squareness of the hysteresis loop is deteriorated with the exposing time to result in losing the hysteresis eventually. In this case, while the Hn deteriorates drastically, the Hc is difficult to decrease. However, if the exposing time of N2 gas is insufficient, a magnetic layer high in the Hc remains at the bottom of the recesses to result in losing the advantages of the DTR medium or BPM. Here, by paying attention to difference in behaviors between the demagnetization caused by He gas and the demagnetization caused by N2 gas, a mixed gas of He+N2 is used, and thereby, while etching the magnetic recording layer, the magnetic recording layer at the bottom of the recesses may efficiently demagnetized.
[Resist Stripping]
After the magnetic recording layer is demagnetized, the UV resist is stripped off. The UV resist is readily stripped off by treating with oxygen plasma. At this time, the etching protective layer made of carbon and remaining on the magnetic recording layer is stripped off as well.
[Protective Film Formation and After-Treatment]
Finally, a carbon protective film is formed. The carbon protective film is desirably formed by CVD from the viewpoint of improving coverage to the protrusions and recesses. However, sputtering or vacuum evaporation may be used. When the CVD method is used, a DLC film containing many sp3-bonded carbons is formed. When a thickness of the carbon protective film is less than 2 nm, the coverage deteriorates and, when the thickness of the carbon protective film exceeds 10 nm, a magnetic spacing between the head and medium becomes larger to unfavorably deteriorate SNR. A lubricant is applied to the protective film. Examples of the lubricant include perfluoropolyether, fluorinated alcohol and fluorinated carboxylic acid.
EXAMPLES Example 1According to the method shown in
The father stamper was set to an injection molding machine and resin stampers were continuously molded under the conditions of mold clamping force of 50 t and a cycle time of 10 seconds. The surface configurations of resin stampers at 10 shots and 10,000 shots were observed with an AFM (atomic force microscope). As a result, remarkable difference was not found between the surface configurations of both resin stampers. Thus, it was found that even when the resin stampers are continuously molded, shapes of the resin stampers are not deteriorated.
Example 2In this Example, the surface roughness (Ra) of the back side of a Ni stamper was studied.
A Ni stamper was prepared in a manner similar to Example 1. The surface roughness (Ra) of the back side of the Ni stamper was 7 nm.
For the purpose of comparison, a Ni stamper was prepared by mechanically polishing by rotating and revolving with a polishing cloth pressed to the back side. The stamper was free from burrs on inner and outer peripheral edges of the back side but had the Ra of 30 nm or more. When the stamper was used to mold resin stampers in a manner similar to Example 1, it was found that the resin stamper is free from deterioration in shape even after 10,000 shots.
Furthermore, for the purpose of comparison, a Ni stamper whose back side is not polished was prepared and the Ni stamper was used to mold resin stampers in a manner similar to Example 1.
The RRO of the above-mentioned three types of resin stampers were evaluated with an optical disk tester (trade name: DDU-1000, manufactured by Pulstec Industrial Co., Ltd.). As a result, it was found that resin stampers injection molded from a stamper having Ra of 7 nm were smaller in the RRO than resin stampers injection molded from the non-polished Ni stamper or a stamper that has the Ra of 30 nm or more.
Furthermore, by varying conditions of buffing, Ni stampers different in the surface roughness (Ra) of the back side were prepared. Resin stampers were prepared from the Ni stampers and the RRO was evaluated in a manner similar to that described above.
Table 1 shows relationship between Ra of back sides of Ni stampers and RRO of resin stampers. From Table 1, it was found that resin stampers prepared from a Ni stamper having Ra of the back side of 7 nm or less are improved in the RRO than resin stampers prepared from a Ni stamper that is not polished. The Ra of the back side of the Ni stamper is preferably as small as possible. However, it is very difficult to make the Ra of the back side of a stamper smaller than the Ra (substantially 0.6 nm) of a substrate. Accordingly, it is said that a Ni stamper having the Ra of the back side of 0.6 to 0.7 nm may actually obtain an effect of reducing the RRO of resin stampers.
A Ni stamper was prepared in a manner similar to Example 1. The Ra of the back side of the stamper was 7 nm. When an in-plane thickness of the stamper was measured, the maximum value was 282 μm, the minimum value was 279 μm, and difference ΔT in thickness was within 3 μm.
Furthermore, stampers to be set to a polishing machine were mirror-polished with levelness thereof varied and thereby several types of Ni stampers having the Ra of the back side of 7 nm and different in the ΔT of in-plane thickness were prepared.
Resin stampers were molded from these Ni stampers. The RRO of each of the resultant resin stampers was evaluated with an optical disk tester (trade name: DDU-1000, manufactured by Pulstec Industrial Co., Ltd.).
The RRO displacement of the resin stamper is preferably 0.5 or less. Thus, ΔT within a stamper plane is preferably 3 μm or less. The ΔT within a Ni stamper plane is preferably as small as possible. However, it is very difficult to make the ΔT smaller than 0.3 μm (substantially one thousandth of the total thickness). Accordingly, it is said that a Ni stamper having the ΔT in the range of 0.3 to 3 μm may actually achieve an effect of reducing the RRO of resin stampers.
Example 4A Ni stamper was prepared in a manner similar to Example 1 except that the stamper slimming shown in
The stamper prepared in Example 1 had a track pitch of 75 nm, a width of protrusions of 25 nm and a width of recesses (corresponding to recording tracks) of 50 nm. The stamper prepared by slimming had a track pitch of 75 nm, a width of protrusions of 15 nm and a width of recesses of 60 nm.
Example 5A Ni stamper (mother stamper) was prepared according to a method shown in
The produced DTR medium had a track pitch of 75 nm, a width of recording tracks of 50 nm and a width of recesses of 25 nm. A lubricant was applied to the surface of the DTR medium. The DTR medium was installed in an HDD to evaluate characteristics thereof. As a result, positioning accuracy of the read/write head was 6 nm, and an on-track BER (bit error rate) was 10−5.
When DTR media or BPMs are produced, a Ni mother stamper or a Ni daughter stamper is preferably used. This is because the same patterns as those of the resist master plate on which patterns are drawn by EB lithography may be transferred on the media.
Example 6After a mother stamper was prepared according to a method described in Example 5, a son stamper was prepared according to a method shown in
The son stamper was set to an injection molding machine and resin stampers were continuously molded under the conditions of mold clamping force of 50 t and a cycle time of 10 seconds. Surface configurations of the resin stampers at 10 shots and 10,000 shots were observed with an AFM (atomic force microscope). As a result, remarkable difference was not found between both surface configurations. It was found that even when the son stamper is used continuously to mold resin stampers, a shape of the resin stamper does not show deterioration. Thus, it was confirmed that, also when the son stamper is used, advantages same as the case where the father stamper was used may be obtained.
Example 7A son stamper was prepared in a manner similar to Example 6. Subsequently, the son stamper was slimmed by immersing in sulfamic acid controlled to pH 2 for 30 minutes. Before slimming, a track pitch was 75 nm, a width of protrusions was 25 nm and a width of recesses (corresponding to recording tracks) was 50 nm. After slimming, a width of protrusions was 15 nm and a width of recesses (corresponding to recording tracks) was 60 nm.
Thereafter, as shown in
The daughter stamper was set in an injection molding machine to prepare resin stampers. As a material of the resin stamper, ZEONOR 1060R (trade name, manufactured by Zeon Corporation) was used. Thereafter, according to the method shown in
The produced DTR medium had a track pitch of 75 nm, a width of recording tracks of 60 nm and a width of recesses of 15 nm. A lubricant was applied to the surface of the DTR medium. The DTR medium was installed on an HDD to evaluate characteristics thereof. As a result, positioning accuracy of the read/write head was 6 nm, and an on-track BER (bit error rate) was 10−6.
The DTR medium produced in the Example is wider by 10 nm in the recording track width than the DTR medium produced in Example 5. Thus, the BER was improved. This effect is due to slimming.
As described above, the Ni mother stamper or Ni daughter stamper is preferably used to produce DTR media and BPMs. It is more preferred to apply stamper slimming during preparation of the son stamper from the viewpoint of mass-productivity. The stamper slimming is wet etching. Thus, unless a chemical management is applied severely, problems such as dust generation and variation of slimming rate are caused. When a father stamper is slimmed, in the case of failing in the slimming, it is necessary to restart from the EB drawing. However, the EB drawing takes such a long time as 3 days to one week and is high in risk. On the other hand, in the case of slimming the son stamper, if failed in the slimming, it is only necessary to prepare again a son stamper from a mother stamper to recover. Therefore, there is only time loss of several hours.
Example 8A BPM was prepared in a manner similar to Example 5 except that patterns shown in
In the BPM, the BER cannot be defined. Thus, an intensity of signal amplitude was evaluated. When the BPM was magnetized in one direction and installed in a drive and a read waveform was observed, the intensity of signal amplitude was 200 mV. Positioning accuracy of the read/write head was 6 nm. It was found that a BPM can be produced according to a method similar to that for a DTR medium.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Claims
1. A stamper comprising:
- patterns corresponding either to recording tracks or to recording bits in a data region and patterns corresponding to information in a servo region in protrusions and recesses on a front side of the stamper,
- wherein an inner periphery and an outer periphery are processed in such a manner that an inner peripheral edge, an outer peripheral edge and a main surface of the back side are on the same plane on a back side.
2. The stamper of claim 1, wherein roughness Ra of the back side is 7 nm or less.
3. The stamper of claim 1, wherein a deviation of thicknesses in the plane is 3 μm or less.
4. A method of producing a stamper, comprising:
- applying an electron beam resist to a substrate;
- drawing pattern corresponding either to recording tracks or to recording bits in a data region, and patterns corresponding to information in a servo region on the electron beam resist by electron beam lithography, followed by developing to form protrusions and recesses;
- forming a conductive film on the protrusions and recesses of the electron beam resist followed by forming a Ni electroforming layer by electroforming;
- peeling off the Ni electroforming layer to form a stamper;
- duplicating a stamper by repeating forming and peeling-off of the Ni electroforming layer, as required; and
- processing an inner periphery and an outer periphery of the stamper followed by polishing a back side of the stamper.
5. The method of claim 4, wherein the stamper is a second stamper duplicated from a first stamper, a third stamper duplicated from the second stamper, or a fourth stamper duplicated from the third stamper.
6. The method of claim 4, comprising:
- peeling off the Ni electroforming layer in order to form the stamper; and
- slimming the resultant stamper.
Type: Application
Filed: Jan 28, 2010
Publication Date: Aug 5, 2010
Applicant: KABUSHIKI KAISHA TOSHIBA (Tokyo)
Inventors: Yoshiyuki KAMATA (Tokyo), Takuya SHIMADA (Kawasaki-shi), Satoshi SHIROTORI (Yokohama-shi), Masatoshi SAKURAI (Tokyo)
Application Number: 12/695,936
International Classification: B29C 59/02 (20060101); G03F 7/20 (20060101);